Why are snowflakes quite big on certain days, and then smaller on other days?
The shape and size of snowflakes ultimately depend on the temperature and the amount of water vapour available in the cloud where the flake first forms, and in the layers of air that the flake falls through as it descends. Some soggy flakes, measuring about 2 cm in diameter when they reach the earth, are conglomerations of 100’s of matted-together flakes which have passed through relatively mild and moist air. On the other hand, dry snow tends to arrive as small, single flakes, unlikely to bind with other flakes as they fall through dry, cold air. Nearly anything can happen to a snowflake as it drifts and tumbles earthward. Pieces break off, evaporate or melt. They bump into each other and sometimes bind together. If the wind is too strong, the big flakes will rip apart and you’ll only see fragments. Also the greater the distance a snowflake falls the larger it usually becomes. About a century ago, monster snowflakes which were larger than a medium-size pizza supposedly fell from the s
The shape and size of an individual snowflake depends on the air temperature and the amount of water vapour available in the cloud where the snowflake forms. In very moist situations where snowflakes fall through a large depth of air near 0C, the snowflake that reaches the ground can be a combination of dozens of matted-together smaller flakes. Snowflakes that form in drier conditions do not join together as easily and therefore, fall as individual smaller flakes. Nearly anything can happen to a snowflake as it falls to the earth. These include pieces of a snowflake breaking off, evaporating into the atmosphere, and joining other falling snowflakes. Additionally, if the wind speed is too great, bigger flakes will be ripped apart and most of the snow will fall as smaller flakes.
